Ink jet recording ink and recording method

ABSTRACT

An ink jet recording method comprising the step of printing two solutions of a first solution and an ink composition is provided which, even in the case of printing on a recycled paper, can realize a good printed image, especially an image having no significant feathering and free from unevenness of printing and an image free from color bleeding. A first solution containing a polyvalent metal salt and/or a polyallylamine is used in combination with an ink composition containing an inorganic oxide colloid, and optionally an epoxy-containing compound. Specifically, the first solution is deposited onto a recording medium, and the ink composition is then deposited by ink jet printing to perform printing.

FIELD OF THE INVENTION

The present invention relates to an ink jet recording method. Moreparticularly, the present invention relates to an ink jet recordingmethod wherein both a reaction solution and an ink composition aredeposited onto a recording medium.

BACKGROUND ART

An ink jet recording method is a printing method wherein droplets of anink composition are ejected and deposited onto a recording medium suchas paper. This method has a feature that an image having a highresolution and a high quality can be realized at a high speed with arelatively inexpensive apparatus. In general, the ink composition usedin the ink jet recording method comprises water as a main component and,added thereto, a colorant and a wetting agent such as glycerin added forprevention of clogging and other purposes.

On the other hand, a new ink jet recording method has been recentlyproposed. The new method comprises applying a polyvalent metal saltsolution onto a recording medium and then applying an ink compositioncontaining a dye having at least one carboxyl group (e.g., JapanesePatent Laid-Open No. 202328/1993). According to this method, polyvalentmetal ions combine with the dye to form an insoluble composite which canprovide an image having water resistance and a high quality free fromcolor bleeding.

Further, an ink jet recording method has been proposed wherein a colorink containing at least a surfactant or a penetrable solvent and a saltfor imparting a penetrating property is used in combination with a blackink which cooperates with the salt to cause thickening or coagulation,thereby providing a high-quality color image having a high image densityand free from color bleeding (Japanese Patent Laid-Open No.106735/1994). More specifically, in this method, two liquids, i.e., afirst liquid containing a salt and a second liquid of an inkcomposition, are printed to provide a good image.

Furthermore, other ink jet recording methods wherein two liquids areprinted have been proposed, for example, in Japanese Patent Laid-OpenNo. 240557/1991 and No. 240558/1991.

In the above ink jet recording method wherein two liquids are printed, aneed still exists for the following properties.

At the outset, an improvement in fixability of the colorant is required.In recent years, recycled papers have become used instead of wood freepapers. For the recycled papers, the penetration of an ink is in generalbetter than that for the wood free papers. For this reason, ahigh-quality image is formed on the wood free papers, whereas featheringor color bleeding is often created in the image formed on the recycledpapers. Therefore, for recycled paper, the elimination of the featheringor color bleeding has been desired in the art.

Secondly, a reduction in uneven printing is required. The unevenprinting refers to a variation in color density in the print derivedfrom localization of a colorant on the paper. Although the unevenprinting poses no significant problem in printing of letters of regularsize, it is a serious problem in applications where figures, graphs andthe like are printed.

Thirdly, broadening the range of usable colorants is required. Most ofink jet recording methods where two liquids are printed utilize asalting-out phenomenon between a metal ion and a carboxyl ion containedin the colorant so that the colorant should have a carboxyl group. Somedyes, however, contain a water-soluble group other than the carboxylgroup. For example, some dyes may dissolve with a sulfonic group. Arecording method which permits the use of dyes having a group other thana carboxyl group has been desired in the art.

SUMMARY OF THE INVENTION

The present inventors have now found that, in the ink jet recordingmethod wherein two liquids are printed, the use of an ink compositionwith an oxide colloid added thereto can provide a good print. Thepresent invention has been made based on such finding.

Accordingly, a general object of the present invention is to provide anink jet recording method involving printing of two liquids which canrealize a good image.

A more specific object of the present invention is to provide an ink jetrecording method involving printing of two liquids which can realize agood image even on recycled paper.

Another object of the present invention is to provide an ink jetrecording method involving printing of two liquids which can realize animage free from uneven printing.

A further object of the present invention is to provide an ink jetrecording method involving printing of two liquids which enables a widerange of colorants to be usable.

The above object can be attained, according to the present invention, byan ink jet recording method comprising the step of depositing a reactionsolution and an ink composition onto a recording medium to performprinting, wherein the reaction solution contains a polyvalent metal saltand/or polyallylamine and the ink composition comprises at least acolorant, an inorganic oxide colloid, and an aqueous solvent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an embodiment of the ink jet recording apparatus accordingto the present invention, wherein a recording head is providedseparately from an ink tank to feed an ink composition and a reactionsolution into a recording head through an ink tube;

FIG. 2 is an enlarged view showing the surface of nozzles for arecording head, wherein reference character 1b designates the surface ofa nozzle for a reaction solution and 1c the surface of a nozzle for anink composition;

FIG. 3 is a diagram illustrating ink jet recording using the recordinghead shown in FIG. 2, wherein numeral 31 designates a region where areaction solution has been deposited and numeral 32 a printed regionwhere an ink composition has been printed on the deposited reactionsolution;

FIG. 4 shows another embodiment of the recording head according to thepresent invention, wherein all ejection nozzles are arranged in lateraldirection;

FIG. 5 shows an embodiment of the ink jet recording apparatus accordingto the present invention, wherein a recording head is integral with anink tank; and

DETAILED DESCRIPTION OF THE INVENTION

Ink jet recording method

The ink jet recording method according to the present inventioncomprises the step of printing a reaction solution and an inkcomposition on a recording medium.

The reaction solution and the ink composition may be applied on arecording medium in any sequence. Specifically, any of the followingmethods may be suitably used: a method wherein a reaction solution isdeposited onto a recording medium followed by deposition of an inkcomposition onto the recording medium with the reaction solutiondeposited thereon, a method wherein an ink composition is printedfollowed by deposition of the reaction solution, and a method wherein areaction solution and an ink composition are mixed together immediatelybefore or immediately after ejection thereof.

According to the ink jet recording method of the present invention, goodprinting can be realized by bringing a reaction solution into contactwith an ink composition. Although the present invention is not intendedto be bound by the following hypothesis, the reason why good printingcan be achieved by the present invention is believed as follows. Uponcontact of the reaction solution with the ink composition, thepolyvalent metal ion or the polyallylamine contained in the reactionsolution breaks the state of dispersion of a colorant, an inorganicoxide colloid, and other ingredients, resulting in agglomeration ofthese ingredients. In particular, the polyvalent metal ion or thepolyallylamine contained in the reaction solution is reacted with theinorganic oxide colloid contained in the ink composition to formagglomerates which inhibit the penetration of the colorant into therecording medium. Colloidal particles left on the recording medium aredeposited onto the recording medium, and the particles are bound to oneanother to form a film, accelerating the fixation of the colorant ontothe recording medium. Thus, an image having high color density and freefrom feathering and uneven printing could be realized. Further, in acolor image, uneven color mixing in boundaries of different colors, thatis, color bleeding, can also be advantageously prevented. The abovemechanism is hypothetical, and the present invention should not beconstrued to be limited by this mechanism.

As described above, in the present invention, the inorganic oxidecolloid is reacted with the polyvalent metal ion or the polyallylaminecontained in the reaction solution to efficiently form agglomerates.Thus, a good printed image can be realized even when the colorant,together with the polyvalent metal ion or the polyallylamine, is lesslikely to form an agglomerate. This means that the method according tothe present invention does not limit the kind of the colorant used andpermits a wide variety of colorants to be used, which is a greatadvantage of the present invention.

The deposition of the reaction solution onto the recording medium may becarried out by any of an embodiment where the reaction solution isselectively deposited on only an area where the ink composition is to bedeposited and an embodiment where the reaction solution is deposited onthe whole surface of paper. The former embodiment can minimize theconsumption of the reaction solution and, hence, is cost-effective. Inthis embodiment, however, an accuracy is required to some extent withrespect to the position where both the reaction solution and the inkcomposition are deposited. On the other hand, for the latter embodiment,the requirement for the accuracy of the position where the reactionsolution and the ink composition are deposited is relaxed as comparedwith the former embodiment. In this embodiment, however, since thereaction solution is deposited in a large amount on the whole surface ofpaper, the paper is likely to cause curling during drying. For the abovereason, the selection of the embodiment may be determined by taking acombination of the ink composition with the reaction solution intoconsideration. In the case of the former embodiment, the deposition ofthe reaction solution can be performed by ink jet recording.

As described below, the reaction solution may contain a colorant so asto function also as an ink composition.

Ink composition

The ink composition used in the present invention comprises at least acolorant, an inorganic oxide colloid, and an aqueous solvent.

Inorganic oxide colloid

The inorganic oxide colloid which is also called "inorganic oxide sol"used in the present invention refers to a colloidal solution comprising:a dispersion medium composed of water or water and an organic solventhaving good compatibility with water; and a dispersoid composed ofultrafine particles of an inorganic oxide. Inorganic oxides usableherein include, but are not limited to, high-molecular weight silicicanhydride (SiO₂) and alumina (Al₂ O₃). The particle diameter of theultrafine particles of the inorganic oxide is generally about 1 to 100nm, preferably 1 to 20 nm, more preferably 1 to 10 nm. The dispersionmedium for the inorganic oxide colloid is generally water or a mixedsolvent composed of water and an organic solvent having goodcompatibility with water, for example, methanol, ethanol, isopropylalcohol, or n-propanol. The inorganic oxide colloid is prepared bydispersing ultrafine particles of the inorganic oxide into water or theabove organic solvent. A dispersion of the ultrafine particles in wateris called an "aqueous sol," and a dispersing of the ultrafine particlesin an organic solvent is called an "organosol."

As described above, the inorganic oxide colloid used in the presentinvention should interact with the polyvalent metal salt and/orpolyallylamine to form agglomerates.

The inorganic oxide colloid may be a commercially available one, andspecific examples thereof include: Snowtex S, Snowtex N, Snowtex C,Snowtex SS, Snowtex XS, Snowtex 20, Snowtex 30, and Snowtex 40,manufactured by Nissan Chemical Industry Ltd., Cataloid SI-350, CataloidSI-500, Cataloid SI-30, Cataloid S-20L, Cataloid S-20H, Cataloid S-30L,Cataloid S-30H, and Cataloid SI-40, manufactured by E. I. du Pont deNemours & Co.), which are dispersions of ultraviolet particles ofhigh-molecular weight silicic anhydride in water; Aluminasol 100,Aluminasol 200, and Aluminasol 520, manufactured by Nissan ChemicalIndustry Ltd., which are dispersions of ultrafine particles of aluminain water; and OSCAL-1432 (isopropyl alcohol sol, manufactured byCatalysts and Chemicals Industries Co., Ltd.) which is a dispersion ofultrafine particles of high-molecular weight silicic anhydride in anorganic solvent. Most of the commercially available colloidal solutionsof inorganic oxides have pH adjusted to the acidic or alkaline. This isbecause the pH region where the inorganic oxide colloid exists stably ison the acidic or alkaline side. Therefore, when the addition of acommercially available inorganic oxide colloidal solution to the ink iscontemplated, it should be made by taking into consideration the pHregion, where the inorganic oxide colloid exists stably, and the pHvalue of the ink.

The amount of the inorganic oxide colloid added may be suitablydetermined by taking into consideration the type and agglomerate. Ingeneral, however, it is preferably about 0.1 to 15% by weight, morepreferably about 0.5 to 5.0% by weight, based on the ink composition. Aplurality of inorganic oxide colloids may be added.

Colorant

The colorant contained in the ink composition according to the presentinvention may be any of a dye and a pigment. In the present invention,the following wide variety of colorants may be utilized.

Dyes usable herein include various dyes commonly used in ink jetrecording, such as direct dyes, acid dyes, foodstuff dyes, basic dyes,reactive dyes, disperse dyes, vat dyes, soluble vat dyes, and reactivedisperse dyes.

Regarding the pigment, inorganic and organic pigments are usable withoutany particular limitation. Examples of the inorganic pigment include, inaddition to titanium oxide and iron oxide, carbon blacks produced byknown processes, such as contact, furnace, and thermal processes.Examples of the organic pigment include azo pigments (including azolake, insoluble azo pigment, condensed azo pigment, and chelate azopigment), polycyclic pigments (for example, phthalocyanine, perylene,perinone, anthraquinone, quinacridone, dioxazine, thioindigo,isoindolinone, and quinophthalone pigments), dye chelates (for example,basic dye chelates and acid dye chelates), nitro pigments, nitrosopigments, and aniline black.

According to a preferred embodiment of the present invention, the abovepigment is preferably added in the form of a pigment dispersion preparedby dispersing the pigment in an aqueous medium with the aid of adispersant or a surfactant. Preferred dispersants include those commonlyused in the preparation of a dispersion of a pigment, for example,polymeric dispersant. In this connection, that the dispersant and thesurfactant contained in the dispersion of the pigment function also asthe dispersant and the surfactant for the ink composition will beapparent to a person having ordinary skill in the art.

The amount of the pigment added to the ink is preferably about 0.5 to25% by weight, more preferably about 2 to 15% by weight.

Aqueous Solvent

The aqueous solvent as a main solvent of the ink composition of thepresent invention comprises basically an water-soluble organic solventand water. The water-soluble organic solvent is preferably a low-boilingorganic solvent, and preferred examples thereof include methanol,ethanol, n-propyl alcohol, iso-propyl alcohol, n-butanol, sec-butanol,tert-butanol, iso-butanol, and n-pentanol. Monohydric alcohols areparticularly preferred. The low-boiling organic solvent has the effectof shortening the time taken for drying the ink.

Further, according to a preferred embodiment of the present invention,the aqueous solvent further comprises a wetting agent comprising ahigh-boiling organic solvent. Preferred examples of high-boiling organicsolvents usable herein include polyhydric alcohols such as ethyleneglycol, diethylene glycol, triethylene glycol, polyethylene glycol,polypropylene glycol, propylene glycol, butylene glycol,1,2,6-hexanetriol, thioglycol, hexylene glycol, glycerin,trimethylolethane, and trimethylolpropane; alkyl ethers of polyhydricalcohols, such as ethylene glycol monomethyl ether, ethylene glycolmonobutyl ether, diethylene glycol monomethyl ether, diethylene glycolmonoethyl ether, diethylene glycol monobutyl ether, triethylene glycolmonomethyl ether, triethylene glycol monoethyl ether, and triethyleneglycol monobutyl ether; urea; 2-pyrrolidone; N-methyl-2-pyrrolidone;1,3-dimethyl-2-imidazolidinone; and triethanolamine.

The amount of the wetting agent added is preferably in the range of from0.5 to 40% by weight, more preferably in the range of from 2 to 20% byweight, based on the ink. The amount of the low-boiling organic solventadded is preferably 0.5 to 10% by weight, more preferably in the rangeof from 1.5 to 6% by weight, based on the ink.

The ink composition used in the present invention may contain asurfactant. Preferred examples thereof include surfactants such asanionic surfactants, nonionic surfactants, and amphoteric surfactants,alcohol such as methanol, and iso-propyl alcohol, and polyalcohol loweralkyl ether such as ethylene glycol mono-methyl ether, diethylene glycolmono-methyl ether, diethylene glycol mono-butyl ether, triethyleneglycol mono-butyl ether, propylene glycol mono-methyl ether, anddipropylene glycol mono-methyl ether.

Further, if necessary, pH adjustors, preservatives, antimolds and thelike may be added. Examples of pH adjustors include KOH, NaOH,triethanolamine.

Saccharide

The ink composition used in the present invention may further comprise asaccharide. The addition of the saccharide can further improve the colordensity, minimizing feathering and uneven printing. Further, in the caseof a color image, color bleeding can be prevented on a high level.Specific examples of saccharides usable herein include monosaccharides,disaccharides, oligosaccharides (including trisaccharides andtetrasaccharides), and other polysaccharides, preferably glucose,mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid,glucitol, sorbitol, maltose, cellobiose, lactose, sucrose, trehalose,and maltotriose. The term "poloysaccharide" used herein meanssaccharides in the broad sense as including substances which existwidely in the world of nature, such as alginic acid, α-cyclodextrin, andcellulose. Derivatives of these saccharides usable herein includereducing sugars of the above saccharides (for example, sugar alcoholsrepresented by the general formula HOCH₂ (CHOH)_(n) CH₂ OH, wherein n isan integer of 2 to 5), oxidizing sugars (for example, aldonic acid oruronic acid), amino acids, and thiosugars. Among them, sugar alcoholsare particularly preferred, and specific examples thereof includemaltitol and sorbitol.

The content of the saccharide is suitably 0.1 to 40% by weight,preferably 0.5 to 30% by weight, based on the ink composition.

Epoxy-containing compound and epoxy curing agent

According to a preferred embodiment of the present invention, the inkcomposition according to the present invention contains anepoxy-containing compound. The term "epoxy-containing compound" usedherein means a compound which has at least two epoxy groups in itsmolecular structure and causes a crosslinking reaction, in which anepoxy group is involved, resulting in resinification (i.e., increasedmolecular weight). The addition of the epoxy-containing compound permitsgood scratch resistance and water resistance to be imparted to theprinted image.

Epoxy-containing compounds usable in the present invention includecompounds containing an epoxy group and, in addition, a functional groupreactive with an epoxy group and compounds containing an epoxy group butnot containing a functional group reactive with an epoxy group.

The term "functional group reactive with an epoxy group" used hereinmeans a functional group which is reacted with an epoxy group to causecrosslinking, and examples of such functional groups include hydroxyl,carboxyl, and sulfonic groups. In the present invention, the use of theepoxy-containing compound having a functional group reactive with anepoxy group can eliminate the need to add an epoxy curing agent,described below, to the reaction solution. On the other hand, theaddition of an epoxy curing agent to the reaction solution incombination with the use of the epoxy-containing compound having afunctional group reactive with an epoxy group results in furtherimproved fixation rate of the print. Any one of these advantages may beselected depending upon situation.

The mechanism through which the addition of an epoxy-containing compoundto the ink composition according to the present invention can offer agood print is believed as follows. However, the following mechanism inhypothetical, and the present invention should not be construed to belimited by this mechanism.

In the method according to the present invention, a reaction solution isand an ink composition are deposited onto a recording medium. Asdescribed above, upon the deposition of the ink composition onto therecording medium, interaction between a polyvalent metal ion derivedfrom a polyvalent metal salt or a polyallylamine in the reactionsolution and an inorganic oxide colloid in the ink composition resultsin agglomeration. When the reaction solution contains an epoxy-curingagent, crosslinking of the epoxy group in the epoxy-containing compoundoccurs resulting in resinification. On the other hand, it is consideredthat when the compound having a functional group reactive with an epoxygroup is used as the epoxy-containing compound, the resinificationproceeds through the following mechanism despite the absence of anepoxy-curing agent. When the distance between the epoxy-containingcompounds is decreased by the agglomeration due to the interactionbetween the polyvalent meal salt or the polyallylamine in the reactionsolution and the inorganic oxide colloid in the ink composition, areaction of the epoxy group with the functional group reactive with theepoxy group would occur among adjacent epoxy-containing compounds. Thisreaction is considered to cause crosslinking among the epoxy-containingcompounds, resulting in resinification. The resinification permits aprinted image to be strongly fixed to the recording medium and, inaddition, results in the formation of a resin film on the surface of theprinted image. Such a print is considered to have good scratchresistance, waterfastness, and lightfastness.

In this context, it should be noted that a reaction between theepoxy-containing compounds each having a functional group reactive withan epoxy group in the ink composition is apparently unfavorable.Therefore, preferably, use of such epoxy-containing compounds inavoided.

Epoxy-containing compounds which may be preferably used in the presentinvention include epoxy-containing resin emulsions and water-solubleepoxy compounds.

According to a preferred embodiment of the present invention,epoxy-containing resin emulsions include an epoxy-containing acrylicresin emulsion comprising: a continuous phase of water; and a dispersedphase comprising a copolymer comprised of recurring units represented bythe following formulae (I) and (II): ##STR1## wherein

R¹ and R³ each independently represent H or CH₃ ;

R² represents a group containing in its structure at least one groupselected from alkyl (with C₁₋₂₁ alkyl being preferred), hydroxyl,carboxyl and sulfonic groups. This resin is not limited by the form ofcopolymers, and, for example, a block copolymer and a random copolymerare possible.

For the above copolymers, the terminal thereof has no essentialinfluence on the properties because the polymer has a high molecularweight. In general, a fragment of a polymerization initiator constitutesthe terminal, and examples of such fragments include fragments ofammonium persulfate and potassium persulfate, such as --OSO₃ H.

Examples of preferred R² include --OH, --COOH, or --COO--R (wherein Rrepresents a straight or branched alkyl group, preferably a C₁₋₁₂ alkylgroup with at least one hydrogen atom on the alkyl group beingoptionally substituted by a hydroxyl, phosphono, or sulfonic group), andan aryl group substituted by a sulfonic group such as for example, aphenyl or tolyl group. Specific examples of the group represented by R²include --OH, --COOH, --COOCH₂ CH₂ OH, --COOCH₂ CH(CH₃)OH, --COOCH₂ CH₂PO(OH)₂, --C₆ H₅ SO₃ H, --COOCH₂ CH₂ SO₃ H, --COOCH₃, --COOC₂ H₅,--COOC₄ H₉, --COOC₆ H₃, --COO(CH₂)₁₁ CH, and --COOCH₂ CH(CH₃)CH₂C(CH₃)₃. In this context, a hydroxyl, carboxyl, or sulfonic group whichmay be contained in R² is a functional group reactive with an epoxygroup. Therefore, when R² contains an alkyl group alone and when R²contains a hydroxyl, carboxyl, or sulfonic group but does notsubstantially react with an epoxy group, the resin emulsion does nothave any functional group reactive with an epoxy group. On the otherhand, when R² contains a hydroxyl, carboxyl, or sulfonic group inaddition to an alkyl group, the resin emulsion has a functional groupreactive with an epoxy group.

Commercially available resin emulsions may be used, and examples thereofinclude Almatex Z116 (manufactured by Mitsui Toatsu Chemicals, Inc.),NEW COAT S2170 and NEW COAT S-1080 (manufactured by Shin-NakamuraChemical Co., Ltd.), VANATEX #952 and VANATEX HG-9 (manufactured byShin-Nakamura Chemical Co., Ltd.), and Piestex B-3 (manufactured byShin-Nakamura Chemical Co., Ltd.).

The water-soluble epoxy compound comprises at least two, per molecule,epoxy groups reactive with an epoxy-curing agent described below, andtypical examples thereof include water-soluble diepoxides. Water-solubleepoxy compounds which may be preferably used in the present inventioninclude compounds represented by the following formula. ##STR2## whereinn is a natural number of 4 to 9.

Examples of preferred water-soluble epoxy compounds include polyethyleneglycol glycidyl ether. Commercially available water-soluble epoxycompounds usable herein include Epolight 400E (polyethylene glycol #400glycidyl ether, manufactured by Kyoeisha Chemical Co., Ltd.), Epolight200E (polyethylene glycol #200 glycidyl ether, manufactured by KyoeishaChemical Co., Ltd.), Epolight 80MF (glycerin diglycidyl ether,manufactured by Kyoeisha Chemical Co., Ltd.), Epiall G-100 (glycerindiglycidyl ether, manufactured by Nippon Oils & Fats Co., Ltd.), andDenacol (manufactured by Nagase Chemicals Ltd.).

Examples of epoxy-containing compounds, having a functional groupreactive with an epoxy group, which may be preferably used in thepresent invention include those, among the above epoxy-containing resinemulsions, wherein at least part of R² contains a functional groupreactive with an epoxy group, that is, a functional group selected fromhydroxyl, carboxyl, and sulfonic groups. It is also possible to use anepoxy-containing compound wherein R² partly contains an alkyl group,preferably a C₁₋₂₁ alkyl, and does not contain any functional groupreactive with an epoxy group. Commercially available epoxy-containingcompounds of the above type include Almatex Z116 (manufactured by MitsuiToatsu Chemicals, Inc.).

The content of the epoxy-containing compound in the ink compositionaccording to the present invention is preferably about 1 to 10% byweight, more preferably 1 to 5% by weight, based on the ink composition.

The ink composition used in the present invention may contain a resinemulsion as described below. When the above epoxy-containing compound isan epoxy-containing resin emulsion, it serves also as the resinemulsion. Therefore, use of an additional resin emulsion is unnecessary.However, according to a preferred embodiment of the present invention,the resin emulsion is added in combination with the epoxy-containingresin emulsion.

In the present invention, preferably, an epoxy-curing agent may beincorporated into the reaction solution. This epoxy-curing agent refersto an agent which, together with the epoxy-containing compound containedin the ink composition, accelerates resinification (an increase inmolecular weight) of the epoxy-containing compound by crosslinking.According to the present invention, any epoxy-curing agent may beutilized without any limitation so far as it can offer a printed imagehaving good scratch resistance and waterfastness in the ink jetrecording method described below.

Epoxy-curing agents which may be preferably used in the presentinvention are typically soluble in water. Examples thereof include aminecompounds, for example, ethylenediamine, diethylaminopropylamine,N-aminoethylpiperazine, trimethylhexamethylenediamine, modifiedaliphatic amines, water-soluble polyamines, water-soluble cold curingcatalysts other than amines, for example, aromatic sulfonic acid, suchas p-phenolsulfonic acid, and curing agents for epoxy emulsions. It isalso possible to utilize commercially available curing agents, andexamples thereof include Almatex H700 (manufactured by Mitsui ToatsuChemicals, Inc.) and EPOKY-H (manufactured by Mitsui Toatsu Chemicals,Inc.).

The concentration of the epoxy-curing agent in the reaction solution ispreferably about 0.1 to 40% by weight, more preferably about 1 to 20% byweight.

According to the present invention, upon printing of an ink compositionon a recording medium with a reaction solution deposited thereon, anepoxy-curing agent contained in the reaction solution is reacted with anepoxy-containing compound contained in the ink composition, to permitcrosslinking of the epoxy-containing compound to proceed. This reactionmay be expressed, for example, by the following formula: ##STR3##

This accelerates the resinification of the epoxy-containing compound (afurther increase in molecular weight of the resin emulsion). The aboveresinification in a printed image formed on a recording medium permitsthe printed image to be strongly adhered to the recording medium and, inaddition, results in the formation of a resin film on the surface of theprinted image. Thus, the print has good scratch resistance,waterfastness, and lightfastness.

Resin emulsion

According to a preferred embodiment of the present invention, the inkcomposition used in the present invention contains a resin emulsion. Apreferred resin emulsion comprises a continuous phase of water and adispersed phase comprising a resin not containing an epoxy group. Asdescribed above, when the epoxy-containing compound is anepoxy-containing resin emulsion, the addition of the resin emulsion isnot essential. Resins usable herein include acrylic resin, vinyl acetateresin, styrene-butadiene resin, vinyl chloride resin,(meth)acrylate-styrene resin, butadiene resin, and styrene resin.

Further, commercially available resin emulsions may also be used, andexamples thereof include Microgel E-1002 and E-5002 (styrene/acrylicresin emulsion, manufactured by Nippon Paint Co., Ltd.), Voncoat 4001(acrylic resin emulsion, manufactured by Dainippon Ink and Chemicals,Inc.), Voncoat 5454 (styrene/acrylic resin emulsion, manufactured byDainippon Ink and Chemicals, Inc.), SAE-1014 (styrene/acrylic resinemulsion, manufactured by Nippon Zeon Co., Ltd.), and Saivinol SK-200(acrylic resin emulsion, manufactured by Saiden Chemical Industry Co.,Ltd).

According to a preferred embodiment of the present invention, the resinis a polymer having a combination of a hydrophilic segment with ahydrophobic segment. The particle diameter of the resin component is notparticularly limited so far as the resin component forms an emulsion.It, however, is preferably not more than about 150 nm, more preferablyabout 5 to 100 nm.

The resin emulsion may be prepared by subjecting a monomer(s) forforming a contemplated resin to dispersion polymerization in wateroptionally in the presence of a surfactant. For example, an emulsion ofan acrylic resin or a styrene/acrylic resin may be prepared bysubjecting an ester of (meth)acrylic acid or alternatively an ester of(meth)acrylic acid in combination with styrene to dispersionpolymerization in water optionally in the presence of a surfactant. Ingeneral, the ratio of the resin component to the surfactant ispreferably about 10:1 to 5:1. When the amount of the surfactant usedfalls within the above range, it is possible to provide an ink which hasgood water resistance in the form of an image and good penetrability.The surfactant is not particularly limited. Preferred examples thereofinclude anionic surfactants (for example, sodiumdodecylbenzenesulfonate, sodium laurate and an ammonium salt of apolyoxyethylene alkyl ether sulfate); nonionic surfactants having 10 ormore of HLB value (for example, a polyoxyethylene alkyl ether, apolyoxyethylene alkyl ester, a polyoxyethylene sorbitan fatty acidester, a polyoxyethylene alkylamine, and a polyoxyethylene alkylamide).They may be used alone or as a mixture of two or more. Further, it isalso possible to use acetylene glycol (OLFINE Y and Surfynol 82, 104,440, 465, and 485 (all the above products being manufactured by AirProducts and Chemicals Inc.).

The ratio of the resin as the component constituting the dispersed phaseto water is suitably 60 to 400 parts by weight based on 100 parts byweight of the resin with 100 to 200 parts by weight, based on 100 partsby weight of the resin, of water being preferred.

The ratio of the resin as the component constituting the dispersed phaseto water is suitably 60 to 400 parts by weight based on 100 parts byweight of the resin with 100 to 200 parts by weight, based on 100 partsby weight of the resin, of water being preferred.

In the ink used in the present invention, the amount of the resinemulsion incorporated therein is preferably such that the amount of theresin component is in the range of from 0.1 to 40% by weight, morepreferably in the range of from 1 to 25% by weight.

For both the resin emulsion containing an epoxy group and the resinemulsion not containing an epoxy group, it is considered thatinteraction between these resin emulsions and the polyvalent metal ioninhibits the penetration of the colorant component and accelerates thefixation of the colorant component to the recording medium.

Reaction solution

The reaction solution used in the present invention basically comprisesa polyvalent metal salt and/or polyallylamine and water. When the inkcomposition contains an epoxy-containing compound, the reaction solutionpreferably further comprises the above-described epoxy-curing agent.

According to the present invention, the polyvalent metal salt containedin the reaction solution may comprise a divalent or higher polyvalentmetal ion and an ion bonded to the polyvalent metal, preferably anitrate ion or a carboxylate ion and is soluble in water.

Furthermore, preferably, the carboxylate ions are derived from asaturated aliphatic monocarboxylic acid having 1 to 6 carbon atoms or acarbocyclic monocarboxylic acid having 7 to 11 carbon atoms. Preferredexamples of the saturated aliphatic monocarboxylic acid having 1 to 6carbon atoms include formic acid, acetic acid, propionic acid, butyricacid, isobutyric acid, valeric acid, isovaleric acid, pivalic acid, andhexanoic acid. Among them, formic acid and acetic acid are particularlypreferred.

A hydrogen atom(s) on the saturated aliphatic hydrocarbon residue in themonocarboxylic acid may be substituted by a hydroxyl group. Preferredexamples of such carboxylic acids include lactic acid.

Preferred examples of the carbocyclic monocarboxylic acid having 6 to 10carbon atoms include benzoic acid and naphthoic acid with benzoic acidbeing more preferred.

Specific examples of polyvalent metallic ions include divalent metallicions, such as Ca²⁺, Cu²⁺, Ni²⁺, Mg²⁺, Zn²⁺, and Ba²⁺, trivalent metallicions, such as Al³⁺, Fe³⁺, and Cr³⁺. Anions include Cl⁻, NO₃ ⁻, I⁻, Br⁻,ClO₃ ⁻, and CH₃ COO⁻.

In particular, a metal salt constituted by Ca²⁺ or Mg²⁺ providesfavorable results in terms of pH of the reaction solution and thequality of prints.

The concentration of the polyvalent metal salt in the reaction solutionmay be suitably determined so as to attain the effect of providing agood print quality and preventing clogging. It, however, is preferablyabout 0.1 to 40% by weight, more preferably about 5 to 25% by weight.

The polyallylamines usable in the reaction solution are cationicpolymers which are soluble in water and can be positively charged inwater. Such polymers include, for example, those represented by thefollowing formulae (2), (3) and (4): ##STR4## wherein X⁻ represents atleast one member selected from chloride, bromide, iodide, nitrate,phosphate, sulfate, acetate and other ions.

In addition, a copolymer of an allylamine with a diallylamine and acopolymer of diallylmethylammmonium chloride with sulfur dioxide mayalso be used.

The content of the polyallylamine and the polyallylamine derivative ispreferably 0.5 to 10% by weight based on the reaction solution.

According to a preferred embodiment of the present invention, thereaction solution may comprise a wetting agent comprising a high-boilingorganic solvent. The high-boiling organic solvent serves to prevent thereaction solution from being concentrated due to evaporation, thuspreventing clogging of a recording head. Preferred examples ofhigh-boiling organic solvents, some of which are those described abovein connection with the ink composition.

Although the amount of the high-boiling organic solvent added is notparticularly limited, it is preferably about 0.5 to 40% by weight, morepreferably about 2 to 20% by weight.

According to a preferred embodiment of the present invention,triethylene glycol mono-butyl ether and glycerine are preferred. Theamount of triethylene glycol mono-butyl ether and glycerine added incombination as the high-boiling organic solvent is preferably in therange of from 10 to 20% by weight, more preferably in the range of from1 to 15% by weight.

Further, a colorant, e.g., yellow, magenta, or cyan colorant, may beadded to the reaction solution so that the colored reaction solution canserve also as the ink composition described below in the paragraph of"Ink composition."

Further, if necessary, pH adjustors, preservatives, antimolds and thelike may be added. Examples of pH adjustors include KOH, NaOH,triethanolamine. The amount of triethanolamine added is preferably inthe range of 0 to 2.0 by weight.

Ink jet recording apparatus

An ink jet recording apparatus for practicing the ink jet recordingmethod according to the present invention will now be described withreference to the accompanying drawings.

FIG. 1 is a diagram showing an embodiment of an ink jet recordingapparatus. In this embodiment, an ink composition and a reactionsolution are accommodated in a tank and fed into a recording headthrough an ink tube. Specifically, a recording head 1 is communicatedwith an ink tank 2 through an ink tube 3. The interior of the ink tank 2is partitioned, and a chamber for an ink composition, optionally aplurality of chambers respectively for a plurality of color inkcompositions, and a chamber for a reaction solution are provided.

The recording head 1 is carried by a carriage 4 and moved along a guide9 by a timing belt 6 driven by a motor 5. On the other hand, paper 7 asa recording medium is placed by a platen 8 at a position facing therecording head 1. In this embodiment, a cap 10 is provided. A suctionpump 11 is connected to the cap 10 in order to conduct the so-called"cleaning operation." The ink composition sucked by the pump 11 isresorvoired in a waste ink tank 13 through a tube 12.

FIG. 2 is an enlarged view showing the surface of nozzles for therecording head 1. In the drawing, the surface of a nozzle for a reactionsolution is indicated by 1b, and a nozzle 21 for ejecting the reactionsolution is provided in the longitudinal direction. On the other hand,the surface of nozzles for the ink composition is indicated by 1c, and ayellow ink composition, a magenta ink composition, a cyan inkcomposition, and a black ink composition are ejected respectivelythrough nozzles 22, 23, 24 and 25.

Further, an ink jet recording method using the recording head shown inFIG. 2 will be described with reference to FIG. 3. The recording head 1is moved in the direction indicated by an arrow A, during which time thereaction solution is ejected through the nozzle 21 to form a reactionsolution-deposited region 31 in a band form on the recording medium 7.Subsequently, the recording medium 7 is transferred by a predeterminedextent in the direction indicated by an arrow B, during which time therecording head 1 is moved the direction opposite to that indicated bythe arrow A and returned to the left end of the recording medium 7, andthe recording head conduct printing using the ink composition on thereaction solution-deposited region 31, thereby forming a print region32.

Further, as shown in FIG. 4, in the recording head 1, it is alsopossible to arrange all nozzles in the lateral direction to construct anozzle assembly. In the drawing, ejection nozzles for a reactionsolution are denoted by 41a and 41b, and a yellow ink composition, amagenta ink composition, a cyan ink composition, and a black inkcomposition are ejected respectively through nozzles 42, 43, 44 and 45.In the recording head according to this embodiment, the recording head1, when reciprocated on the carriage, can conduct printing in bothdirections. Therefore, in this case, printing at a higher speed isexpected as compared with the case where the recording head shown inFIG. 2 is used.

Further, when the reaction solution and the ink composition arepreferably adjusted so as to fall within the surface tension rangesdescribed above, a high-quality print can be more stably providedregardless of the order of deposition of the reaction solution and theink composition. In this case, even the provision of a single ejectionnozzle suffices for satisfactory results. For example, in the drawing,the nozzle 41b may be omitted. This can contribute to a furtherreduction in size of the head and a further increase in printing speed.

In the ink jet recording apparatus, the supplement of the inkcomposition may be carried out by replacing an ink tank in a cartridgeform. The ink tank may be integral with the recording head. A preferredembodiment of an ink jet recording apparatus using such an ink tank isshown in FIG. 5. In the drawing, the same members as used in theapparatus shown in FIG. 1 have the same reference numerals. In theembodiment shown in FIG. 5, recording heads 1a and 1b are integralrespectively with ink tanks 2a and 2b. An ink composition and a reactionsolution are ejected respectively through the recording heads 1a and 1b.Basically, printing may be conducted in the same manner as describedabove in connection with the apparatus shown in FIG. 1. Further, in thisembodiment, the recording head 1a is moved together with the ink tank 2aon a carriage 4, while the recording head 1a is moved together with theink tank 2b on the carriage 4.

EXAMPLES

The present invention will now be described in more detail withreference to the following examples, though it is not limited to theseexamples only.

Preparation of ink compositions

The following ink compositions were prepared.

    ______________________________________                                        Black ink A1                                                                  ______________________________________                                        Carbon black MA7      5%          by weight                                   (manufactured by Mitsubishi Kasei Corp.)                                      Styrene/acrylic acid copolymer                                                                      1%          by weight                                   (dispersant)                                                                  Snowtex S             10%         by weight                                   (colloidal silica, SiO.sub.2 content 30%,                                     manufactured by Nissan Chemical                                               Industry Ltd.)                                                                Sucrose               0.7%        by weight                                   Maltitol              6.3%        by weight                                   Glycerin              10%         by weight                                   2-Pyrrolidone         2%          by weight                                   Ethanol               4%          by weight                                   Pure water            Balance                                                 ______________________________________                                    

Carbon black and the dispersant were mixed together and dispersed bymeans of a sand mill (manufactured by Yasukawa Seisakusho) with glassbeads (diameter: 1.7 mm, amount: 1.5 times, by weight, the amount of themixture) for 2 hr. Thereafter, the glass beads were removed, and theremaining additives were added, and the mixture was stirred at roomtemperature for 20 min and then filtered through a 5-μm membrane filterto prepare an ink for ink jet recording.

    ______________________________________                                        Black ink A2                                                                  Carbon black Raven 1080                                                                             5%          by weight                                   (manufactured by Columbian Carbon)                                            Styrene/acrylic acid copolymer                                                                      1%          by weight                                   (dispersant)                                                                  Snowtex C             0.5%        by weight                                   (colloidal silica, (SiO.sub.2 content 20%),                                   manufactured by Nissan Chemical                                               Industry Ltd.)                                                                Sucrose               0.7%        by weight                                   Maltitol              6.3%        by weight                                   Glycerin              10%         by weight                                   2-Pyrrolidone         2%          by weight                                   Ethanol               4%          by weight                                   Pure water            Balance                                                 Black ink A3                                                                  Carbon black Raven 1080                                                                             5%          by weight                                   Styrene/acrylic acid copolymer                                                                      1%          by weight                                   (dispersant)                                                                  Snowtex S             5%          by weight                                   Voncoat 4001          5%          by weight                                   (acrylic resin emulsion, resin                                                content 50%, MFT 5° C., manufactured                                   by Dainippon Ink and Chemicals, Inc.)                                         Sucrose               0.7%        by weight                                   Maltitol              6.3%        by weight                                   Glycerin              10%         by weight                                   2-Pyrrolidone         2%          by weight                                   Ethanol               4%          by weight                                   Pure water            Balance                                                 Black ink A4                                                                  C.I. Food Black       2%          by weight                                   Snowtex C             10%         by weight                                   2-Pyrrolidone         5%          by weight                                   Pure water            Balance                                                 Black ink A5                                                                  C.I Food Black        2%          by weight                                   Aluminasol-200        5%          by weight                                   (Al.sub.2 O.sub.3 content 10%, manufactured                                   by Nissan Chemical Industry Ltd.)                                             2-Pyrrolidone         5%          by weight                                   Pure water            Balance                                                 Black ink A6                                                                  C.I. Food Black       2%          by weight                                   2-Pyrrolidone         5%          by weight                                   Pure water            Balance                                                 Black ink A7                                                                  Carbon black Raven 1080                                                                             5%          by weight                                   Styrene/acrylic acid copolymer                                                                      1%          by weight                                   (dispersant)                                                                  Sucrose               0.7%        by weight                                   Maltitol              6.3%        by weight                                   Glycerin              10%         by weight                                   2-Pyrrolidone         2%          by weight                                   Ethanol               4%          by weight                                   Pure water            Balance                                                 The following colorants were added to the following                           liquid media to prepare cyan, magenta, and yellow ink                         compositions as a color ink set.                                              Color ink set A1                                                              Dye                                                                           Cyan ink              3%          by weight                                   C.I. Direct Blue 86                                                           Magenta ink           3%          by weight                                   C.I. Direct Red 9                                                             Yellow ink            3%          by weight                                   C.I. Acid Yellow 23                                                           Liquid medium                                                                 Snowtex C             5%          by weight                                   Diethylene glycol     10%         by weight                                   Surfynol 82           3%          by weight                                   Surfynol TG           0.5%        by weight                                   Pure water            Balance                                                 Color ink set A2                                                              Pigment                                                                       Cyan ink              2%          by weight                                   Pigment KETBLUEEX-1                                                           (manufactured by Dainippon Ink                                                and Chemicals, Inc.)                                                          Magenta ink           2%          by weight                                   Pigment KETRED 309                                                            (manufactured by Dainippon Ink                                                and Chemicals, Inc.)                                                          Yellow ink            2%          by weight                                   Pigment KETYELLOW 403                                                         (manufactured by Dainippon Ink                                                and Chemicals, Inc.)                                                          Liquid medium                                                                 Styrene/acrylic acid copolymer                                                                      0.4%        by weight                                   (dispersant)                                                                  Colloidal silica S    3%          by weight                                   Sucrose               0.7%        by weight                                   Maltitol              6.3%        by weight                                   Glycerin              10%         by weight                                   2-Pyrrolidone         2%          by weight                                   Ethanol               4%          by weight                                   Pure Water            Balance                                                 The following ingredients were mixed together to                              prepare reaction solutions.                                                   Reaction solution A1                                                          Magnesium acetate hexahydrate                                                                       25%         by weight                                   (magnesium acetate    14.8%       by weight)                                  Diethylene glycol     10%         by weight                                   Pure water            Balance                                                 Reaction solution A2                                                          Calcium chloride      10%         by weight                                   Diethylene glycol     10%         by weight                                   Pure water            Balance                                                 Reaction solution A3                                                          The following dyes were added to the following liquid                         medium to prepare reaction solutions serving also as cyan,                    magenta, and yellow color ink compositions.                                   Dye                                                                           Cyan ink              3%          by weight                                   C.I. Direct Blue 86                                                           Magenta ink           3%          by weight                                   C.I. Direct Red 9                                                             Yellow ink            3%          by weight                                   C.I. Acid Yellow 23                                                           Liquid medium                                                                 Calcium chloride      10%         by weight                                   Glycerin              10%         by weight                                   Pure water            Balance                                                 ______________________________________                                    

The above ink compositions and reaction solutions were combined asspecified in Table 1, and the combinations were evaluated by testsdescribed below.

                  TABLE 1                                                         ______________________________________                                                           Color ink                                                                              Reaction                                                  Black ink  set      solution                                          ______________________________________                                        Example A-1                                                                             A1           --       A1                                            A-2       A2           --       A2                                            A-3       A3           --       A2                                            A-4       A4           --       A2                                            A-5       A5           --       A1                                            A-6       A1           A1       A2                                            A-7       A1           A2       A2                                            A-8       A1           --       A3                                            A-9       A1           --       --                                            Comparative                                                                   Example A1                                                                              A5           --       --                                            A2        A6           --       A2                                            A3        A6           --       --                                            ______________________________________                                    

Evaluation A1: Print quality (feathering)

An ink jet printer MJ-700V2C (manufactured by Seiko Epson Corporation)was used to perform printing on the following various papers. In theprinting, the reaction solution was first printed (100% duty), and theblack ink was then used to print a letter. After drying, the prints wereinspected for feathering in the letter.

(1) Xerox P Paper (Xerox Corp.)

(2) Ricopy 6200 Paper (Ricoh Co. Ltd.)

(3) Xerox 4024 Paper (Xerox Corp.)

(4) Neenah Bond Paper (Kimberly-Clark)

(5) Xerox R Paper (recycled paper, Xerox Corp.)

(6) Yamayuri (recycled paper, Honshu Paper Co., Ltd.)

The results were as tabulated in Table 2. Regarding the results given inthe table, the evaluation criteria are as follows.

◯: Sharp print without any feathering

Δ: Feathering observed

X: Remarkable feathering observed rendering the outline of the letterblurry

Evaluation A2: Unevenness of printing

An ink jet printer MJ-700V2C was used to perform printing (100% duty) onthe following various papers. The printing method was the same asdescribed above in connection with the evaluation of the print quality(feathering).

(1) Ricopy 6200 Paper (Ricoh Co. Ltd.)

(2) Canon dry Paper (Canon Inc.)

For the resultant print images, the reflection OD was measured withMacbeth PCMII (manufactured by Macbeth). This measurement was performedfor randomly selected five points in the print area, and the average ofthe measured values was determined. This procedure was repeated fivetimes, and the maximum value and the minimum value in the five averagevalues were determined. When the difference between the maximum valueand the minimum value is less than 0.5, there is no problem forpractical use with the difference being preferably less than 0.4. Theresults were as tabulated in Table 2. In the results given in the table,the evaluation criteria were as follows.

◯: OD difference of less than 0.3

Δ: OD difference of 0.3 to less than 0.4

X: OD difference of not less than 0.4

Evaluation A3: Rubbing property

An ink jet printer MJ-700V2C was used to perform printing on Xerox Ppaper (manufactured by Xerox Corp.), and the resultant prints wereair-dried for 24 hr. The prints were rubbed with a finger under anenvironment of 25° C. and 50% RH and then observed by visible inspectionfor the presence of a stain on the print. The results were as tabulatedin Table 2. In the table, the evaluation criteria were as follows.

◯: No stain observed in the print

Δ: Slight stain observed in the print with the letter being stilllegible

X: Stain observed in the print rendering the letter illegible

Evaluation A4: Color bleeding

An ink jet printer MJ-700V2C was used in this evaluation test. Thereaction solution was deposited (100% duty) on the following recordingmedia, and color inks (cyan, magenta, and yellow) (100% duty) and theblack ink (a letter) were simultaneously printed to examine the printsfor the presence of uneven color-to-color mixing in the letterboundaries. In this case, in Example 8, the reaction solution (100%duty) and the black ink (a letter) were simultaneously printed.

(1) Xerox P Paper (Xerox Corp.)

(2) Ricopy 6200 Paper (Ricoh Co. Ltd.)

(3) Xerox 4024 Paper (Xerox Corp.)

(4) Neenah Bond Paper (Kimberly-Clark)

(5) Xerox R Paper (recycled paper, Xerox Corp.)

(6) Yamayuri (recycled paper, Honshu Paper Co.)

The results were as tabulated in Table 2. In the table, the evaluationcriteria were as follows.

◯: No color-to-color mixing observed with clear letter boundaries

Δ: Feather-like color-to-color mixing observed

X: Significant color-to-color mixing observed rendering the outline ofthe letter blurry.

Evaluation A5: Fixability onto specialty media

An ink jet printer MJ-700V2C was used to print an ink on a specialtygloss paper for MJ-700V2C (manufactured by Seiko Epson Corporation), andthe resultant prints were air-dried for 24 hr. The prints were rubbedwith a finger under an environment of 25° C. and 50% RH and thenvisually inspected for the presence of a stain on the print and theseparation of the colorant. The results were as tabulated in Table 2. Inthe table, the evaluation criteria were as follows.

◯: Neither stain nor separated colorant observed in the print

Δ: Slight stain observed in the print with separated colorant notobserved in the print

X: Both stain and separated colorant observed in the print

                  TABLE 2                                                         ______________________________________                                        Evaluation                                                                             A1      A2    A3        A4  A5                                       ______________________________________                                        Example                                                                       A1         ◯                                                                           ◯                                                                       ◯                                                                         --  --                                     A2         Δ   ◯                                                                       ◯                                                                         --  --                                     A3         ◯                                                                           ◯                                                                       ◯                                                                         --  --                                     A4         Δ   ◯                                                                       ◯                                                                         --  --                                     A5         Δ   ◯                                                                       ◯                                                                         --  --                                     A6         ◯                                                                           ◯                                                                       ◯                                                                         Δ                                                                           Δ                                A7         ◯                                                                           ◯                                                                       ◯                                                                         ◯                                                                     ◯                          A8         ◯                                                                           ◯                                                                       ◯                                                                         Δ                                                                           Δ                                A9         --        --    --      --  --                                     Comparative                                                                   Example                                                                       A1         X         Δ                                                                             Δ --  --                                     A2         Δ   X     X       --  --                                     A3         --        --    --      --  X                                      ______________________________________                                    

The following ink compositions were prepared

    ______________________________________                                        Black ink B1                                                                  Carbon black MA7      5%          by weight                                   (manufactured by Mitsubishi                                                   Kasei Corp.)                                                                  Styrene/acrylic acid copolymer                                                                      1%          by weight                                   (dispersant)                                                                  Almatex Z116          3%          by weight                                   (epoxy-containing acrylic resin                                               emulsion, resin content 5.0%,                                                 manufactured by Mitsui Toatsu                                                 Chemicals, Inc.)                                                              Snowtex S             2%          by weight                                   (colloidal silica, SiO.sub.2 content 30%,                                     manufactured by Nissan Chemical                                               Industry Ltd.)                                                                Sucrose               0.7%        by weight                                   Maltitol              6.3%        by weight                                   Glycerin              10%         by weight                                   2-Pyrrolidone         2%          by weight                                   Triethanolamine       1.0%        by weight                                   (pH adjustor)                                                                 KOH (pH adjustor)     0.1%        by weight                                   Pure water            Balance                                                 Black ink B2                                                                  Carbon black Raven 1080                                                                             5%          by weight                                   (manufactured by Columbian                                                    Carbon Co., Ltd.)                                                             Styrene/acrylic acid copolymer                                                                      1%          by weight                                   (dispersant)                                                                  Almatex Z116          3%          by weight                                   (epoxy-containing acrylic resin                                               emulsion, resin content 50%,                                                  manufactured by Mitsui Toatsu                                                 Chemicals, Inc.)                                                              Epolight 400E         2%          by weight                                   (water-soluble epoxy compound,                                                polyethylene glycol #400                                                      glycidyl ether, manufactured                                                  by Kyoeisha Chemical Co., Ltd.)                                               Snowtex C             1%          by weight                                   (colloidal silica, SiO.sub.2 content 20%,                                     manufactured by Nissan Chemical                                               Industry Ltd.)                                                                Sucrose               0.7%        by weight                                   Maltitol              6.3%        by weight                                   Glycerin              10%         by weight                                   2-Pyrrolidone         2%          by weight                                   Ethanol               4%          by weight                                   Pure water            Balance                                                 Black ink B3                                                                  Carbon black Raven 1080                                                                             5%          by weight                                   Styrene/acrylic acid copolymer                                                                      1%          by weight                                   (dispersant)                                                                  Microgel E-5002       3.5%        by weight                                   (styrene/acrylic resin emulsion,                                              resin content 29.2%,                                                          MFT about 80° C., manufactured                                         by Nippon Paint Co., Ltd.)                                                    Almatex Z116          5%          by weight                                   (epoxy-containing acrylic resin                                               emulsion resin content 50%,                                                   manufactured by Mitsui Toatsu                                                 Chemicals, Inc.)                                                              Snowtex S             1%          by weight                                   Sucrose               0.7%        by weight                                   Maltitol              6.3%        by weight                                   Glycerin              10%         by weight                                   2-Pyrrolidone         2%          by weight                                   Triethanolamine       1.0%        by weight                                   (pH adjustor)                                                                 KOH (pH adjustor)     0.1%        by weight                                   Pure water            Balance                                                 Black ink B4                                                                  Carbon black Raven 1080                                                                             5%          by weight                                   (manufactured by Columbian                                                    Carbon Co., Ltd.)                                                             Styrene/acrylic acid copolymer                                                                      1%          by weight                                   (dispersant)                                                                  Microgel E-5002       3.5%        by weight                                   (styrene/acrylic resin emulsion,                                              resin content 29.2%,                                                          MFT about 80° C., manufactured                                         by Nippon Paint Co, Ltd.)                                                     Epolight 400E         2%          by weight                                   (water-soluble epoxy compound,                                                polyethylene glycol #400                                                      glycidyl ether, manufactured                                                  by Kyoeisha Chemical Co., Ltd.)                                               Snowtex C             1%          by weight                                   (colloidal silica, SiO.sub.2 content 20%,                                     manufactured by Nissan Chemical                                               Industry Ltd.)                                                                Sucrose               0.7%        by weight                                   Maltitol              6.3%        by weight                                   Glycerin              10%         by weight                                   2-Pyrrolidone         2%          by weight                                   Ethanol               4%          by weight                                   Pure water            Balance                                                 Black ink B5                                                                  Carbon black Raven 1080                                                                             5%          by weight                                   (manufactured by Columbian                                                    Carbon Co., Ltd.)                                                             Styrene/acrylic acid copolymer                                                                      1%          by weight                                   (dispersant)                                                                  Sucrose               0.7%        by weight                                   Maltitol              6.3%        by weight                                   Glycerin              10%         by weight                                   2-Pyrrolidone         2%          by weight                                   Ethanol               4%          by weight                                   Pure water            Balance                                                 Black ink B6                                                                  Carbon black Raven 1080                                                                             5%          by weight                                   (manufactured by Columbian                                                    Carbon Co., Ltd.)                                                             Styrene/acrylic acid copolymer                                                                      1%          by weight                                   (dispersant)                                                                  Microgel E-5002       3.5%        by weight                                   (styrene/acrylic resin emulsion,                                              resin content 29.2%,                                                          MFT about 80° C., manufactured                                         by Nippon Paint Co., Ltd.)                                                    Sucrose               0.7%        by weight                                   Maltitol              6.3%        by weight                                   Glycerin              10%         by weight                                   2-Pyrrolidone         2%          by weight                                   Ethanol               4%          by weight                                   Pure water            Balance                                                 ______________________________________                                    

The above black inks were prepared as follows. Carbon black and thedispersant were mixed together and dispersed by means of a sand mill(manufactured by Yasukawa Seisakusho) with glass beads (diameter: 1.7mm, amount; 1.5 times, by weight, the amount of the mixture) for 2 hr.Thereafter, the glass beads were removed, and the remaining additiveswere added, and the mixture was stirred at room temperature for 20 minand then filtered through a 5-μm membrane filter to prepare an ink forink jet recording.

    ______________________________________                                        Color ink set B1                                                              Cyan ink                                                                      Pigment KETBLUX-1     2%          by weight                                   (manufactured by Dainippon Ink                                                and Chemicals, Inc.)                                                          Styrene/acrylic acid copolymer                                                                      1%          by weight                                   (dispersant)                                                                  Almatex Z116          3%          by weight                                   (epoxy-containing acrylic resin                                               emulsion, resin content 50%,                                                  manufactured by Mitsui Toatsu                                                 Chemicals, Inc.)                                                              Snowtex S             2%          by weight                                   (colloidal silica, SiO.sub.2 content 30%,                                     manufactured by Nissan Chemical                                               Industry Ltd.)                                                                Sucrose               0.7%        by weight                                   Maltitol              6.3%        by weight                                   Glycerin              10%         by weight                                   2-Pyrrolidone         2%          by weight                                   Ethanol               4%          by weight                                   Pure water            Balance                                                 Magenta ink                                                                   Pigment KETRED309     2%          by weight                                   (manufactured by Dainippon Ink                                                and Chemicals, Inc.)                                                          Styrene/acrylic acid copolymer                                                                      1%          by weight                                   (dispersant)                                                                  Almatex Z116          3%          by weight                                   (epoxy-containing acrylic resin                                               emulsion, resin content 50%,                                                  manufactured by Mitsui Toatsu                                                 Chemicals, Inc.)                                                              Snowtex S             2%          by weight                                   (colloidal silica, SiO.sub.2 content 30%,                                     manufactured by Nissan Chemical                                               Industry Ltd.)                                                                Sucrose               0.7%        by weight                                   Maltitol              6.3%        by weight                                   Glycerin              10%         by weight                                   2-Pyrrolidone         2%          by weight                                   Ethanol               4%          by weight                                   Pure water            Balance                                                 Yellow ink                                                                    Pigment KETYELLOW403  2%          by weight                                   (manufactured by Dainippon Ink                                                and Chemicals, Inc.)                                                          Almatex Z116          3%          by weight                                   (epoxy-containing acrylic resin                                               emulsion, (resin content 50%),                                                manufactured by Mitsui Toatsu                                                 Chemicals, Inc.)                                                              Snowtex S             2%          by weight                                   (colloidal silica, (SiO.sub.2 content 30%),                                   manufactured by Nissan Chemical                                               Industry Ltd.)                                                                Sucrose               0.7%        by weight                                   Maltitol              6.3%        by weight                                   Glycerin              10%         by weight                                   2-Pyrrolidone         2%          by weight                                   Ethanol               4%          by weight                                   Pure water            Balance                                                 Color ink set B2                                                              Cyan ink                                                                      Pigment KETBLUEEX-1   2%          by weight                                   (manufactured by Dainippon Ink                                                and Chemicals, Inc.)                                                          Styrene/acrylic acid copolymer                                                                      1%          by weight                                   (dispersant)                                                                  Sucrose               0.7%        by weight                                   Maltitol              6.3%        by weight                                   Glycerin              10%         by weight                                   2-Pyrrolidone         2%          by weight                                   Ethanol               4%          by weight                                   Pure water            Balance                                                 Magenta ink                                                                   Pigment KETRED309     2%          by weight                                   (manufactured by Dainippon Ink                                                and Chemicals, Inc.)                                                          Styrene/acrylic acid Copolymer                                                                      1%          by weight                                   (dispersant)                                                                  Sucrose               0.7%        by weight                                   Maltitol              6.3%        by weight                                   Glycerin              10%         by weight                                   2-Pyrrolidone         2%          by weight                                   Ethanol               4%          by weight                                   Pure water            Balance                                                 Yellow ink                                                                    Pigment KETYELLOW403  2%          by weight                                   (manufactured by Dainippon Ink                                                and Chemicals, Inc.)                                                          Sucrose               0.7%        by weight                                   Maltitol              6.3%        by weight                                   Glycerin              10%         by weight                                   2-Pyrrolidone         2%          by weight                                   Ethanol               4%          by weight                                   Pure water            Balance                                                 ______________________________________                                    

The above color ink compositions were prepared as follows. The pigmentand the dispersant were mixed together and dispersed by means of a sandmill (manufactured by Yasukawa Seisakusho) with glass beads (diameter:1.7 mm, amount: 1.5 times, by weight, the amount of the mixture) for 2hr. Thereafter, the glass beads were removed, and the remainingadditives were added, and the mixture was stirred at room temperaturefor 20 min and then filtered through a 5-μm membrane filter to preparean ink composition.

    ______________________________________                                        Reaction solution B1                                                          Magnesium nitrate hexahydrate                                                                    25%           by weight                                    Triethylene glycol monobutyl ether                                                               10%           by weight                                    Glycerin           20%           by weight                                    Pure water         Balance                                                    Reaction solution B2                                                          Magnesium nitrate hexahydrate                                                                    25%           by weight                                    Water-soluble polyamine                                                                          3%            by weight                                    (Almatex H700, manufactured by                                                Mitsui Toatsu Chemicals, Inc.)                                                Triethylene glycol monobutyl ether                                                               10%           by weight                                    Glycerin           20%           by weight                                    Pure water         Balance                                                    ______________________________________                                    

The above reaction solutions were prepared by mixing the ingredientstogether, stirring the mixture at room temperature for one hr, andsubjecting the stirred mixture to suction filtration through a 5μm-membrane filter at room temperature.

Print evaluation test

Predetermined printing was carried out using combinations of the aboveink compositions with the above reaction solutions. The printed imagesthus obtained were evaluated as follows.

Printing method

An ink jet printer MJ-700V2C (manufactured by Seiko Epson Corporation)was used to perform printing on the following various papers. In theprinting, the reaction solution was first printed (100% duty), and theblack ink was used to print a letter. In this case, for both thereaction solution and the ink, the amount of the ink ejected was 0.07μg/dot with the density being 360 dpi. Papers for printing test:

(1) Xerox P Paper (Xerox Corp.)

(2) Ricopy 6200 Paper (Ricoh Co. Ltd.)

(3) Xerox 4024 Paper (Xerox Corp.)

(4) Neenah Bond Paper (Kimberly-Clark)

(5) Xerox R Paper (recycled paper, Xerox Corp.)

(6) Yamayuri (recycled paper, Honshu Paper Co., Ltd.)

Evaluation B1: Rubbing resistance test (line marking resistance)

The resultant prints were air-dried and then rubbed with a water-baseyellow fluorescent marker pen (ZEBRA PEN 2, manufactured by ZEBRA) at amarking force of 4.9×10⁵ N/m², and the degree of stain in the yellowarea was visually inspected. The results were evaluated based on thefollowing criteria.

⊚: No stain created by marking twice immediately after printing

◯: No stain created by marking twice 24 hr after printing

Δ: No stain created by marking once with some paper being stained bymarking twice or 24 hr after printing

X: Some paper stained by marking once 24 hr after printing

Evaluation B2: Print quality (feathering)

Letters after drying the resultant prints were inspected for feathering,and the results were evaluated as follows.

⊚: Sharp without any feathering for all the papers

◯: Feathering observed for some papers (recycled paper)

Δ: Feathering observed for all the papers

X: Remarkable feathering observed rendering the outline of the letterblurry

Evaluation B3: OD value

The reflection optical density (OD) of prints provided by the abovemethod was measured with Macbeth PCMII (manufactured by Macbeth).

The reaction solutions and the ink compositions used in the evaluationsB1 to B3, and the results of evaluation were as tabulated in Table 3.

                  TABLE 3                                                         ______________________________________                                                Reaction Black  Evaluation                                                    solution ink    B1       B2  B3                                       ______________________________________                                        Example                                                                       B1        B1         B1     ◯                                                                        ⊚                                                                  1.65                                   B2        B1         B2     ◯                                                                        ⊚                                                                  1.62                                   B3        B1         B3     ◯                                                                        ⊚                                                                  1.60                                   B4        B1         B4     ◯                                                                        ⊚                                                                  1.59                                   B5        B2         B1     ⊚                                                                     ⊚                                                                  1.68                                   B6        B2         B2     ⊚                                                                     ⊚                                                                  1.65                                   B7        B2         B3     ⊚                                                                     ⊚                                                                  1.63                                   B8        B2         B4     ⊚                                                                     ⊚                                                                  1.62                                   Comparative                                                                   Example                                                                       B1        B1         B5     X      X   1.32                                   B2        B1         B6     Δ                                                                              ◯                                                                     1.42                                   ______________________________________                                    

Evaluation B4: Color bleed

An ink jet printer MJ-700V2C was used in this evaluation test. Thereaction solution was deposited (100% duty) on the above various papersas a recording paper, and color inks (cyan, magenta, and yellow) (100%duty) were simultaneously printed. The prints were visually inspectedfor the presence of uneven color-to-color mixing in the boundariesbetween the colors. The results were evaluated based on the followingcriteria:

◯: No color-to-color mixing observed.

Δ: Feather-like color-to-color mixing observed.

X: Significant color-to-color mixing observed.

The results were as tabulated in Table 4.

                  TABLE 4                                                         ______________________________________                                                 Reaction   Color ink                                                                              Evalua-                                                   solution   set      tion B4                                          ______________________________________                                        Example B9 B1           B1       ◯                                B10        B2           B1       ◯                                Comparative                                                                              B1           B2       X                                            Example B3                                                                    ______________________________________                                    

Evaluation B5: Fixation of ink on specialty medium

(part 1)

An ink jet printer MJ-700V2C (manufactured by Seiko Epson Corporation)was used to perform printing on a specialty gloss film for the ink jetprinter MJ-700V2C (manufactured by Seiko Epson Corporation), and theresultant prints were air-dried for 24 hr. The prints were examined inthe same manner as described in Evaluation B1. The results wereevaluated based on the following criteria:

◯: No stain created in the print by rubbing once

Δ: Slight stain created in the print by rubbing once

X: Stain created in the print by rubbing once

Evaluation B6: Fixation of ink on specialty medium

(part 2)

A pressure-sensitive adhesive tape (cellophane tape: Sekisui Tape,manufactured by Sekisui Chemical Co., Ltd.) was applied to the printedarea in the prints, rubbed twice or thrice with a finger, and thenpeeled off. Thereafter, the printed area from which thepressure-sensitive adhesive tape has been peeled off was visuallyinspected, and the results were evaluated based on the followingcriteria:

◯: Ink (colorant) not separated from the surface of the specialty glossfilm

Δ: Ink present in both the surface of the specialty gloss film and thesurface of a pressure-sensitive adhesive in the pressure-sensitiveadhesive tape

X: Ink (colorant) completely separated from the surface of the specialtygloss film

The results were as tabulated in Table 5.

                  TABLE 5                                                         ______________________________________                                                            Evalua- Evalua-                                                    Black ink  tion B5 tion B6                                           ______________________________________                                        Example                                                                       B11        B1           ◯                                                                         ◯                                 B12        B2           ◯                                                                         ◯                                 B13        B3           ◯                                                                         ◯                                 B14        B4           ◯                                                                         ◯                                 Comparative                                                                   Example                                                                       B5         B5           X       X                                             B6         B6           Δ Δ                                       ______________________________________                                    

What is claimed is:
 1. An ink jet recording method comprising the step of: depositing a reaction solution and an ink composition onto a recording medium to perform printing,wherein the reaction solution contains a polyvalent metal salt and/or a polyallylamine, wherein the ink composition comprises at least a colorant, an inorganic oxide colloid, and an aqueous solvent.
 2. The method according to claim 1, wherein the ink composition further comprises a saccharide.
 3. The method according to claim 1, wherein the colorant is a pigment.
 4. The method according to claim 1, wherein the inorganic oxide colloid is colloidal silica.
 5. The method according to claim 1, wherein the polyvalent metal salt is composed of nitric acid ion or a salt of carboxylic acid ion and polyvalent metal ion.
 6. The ink jet recording method according to claim 5, wherein the carboxylic acid ion is derived from a saturated aliphatic monocarboxylic acid having 1 to 6 carbon atoms where a hydrogen atom(s) on the saturated aliphatic hydrocarbon residue of the monocarboxylic acid may be substituted by a hydroxyl group; or a carbocyclic monocarboxylic acid having a 6 to 10 carbon atoms.
 7. The method according to claim 1, wherein the reaction solution is deposited onto a recording medium followed by printing the ink composition on the recording medium.
 8. The method according to claim 1, wherein the ink composition is deposited onto a recording medium followed by deposition of the reaction solution onto the recording medium.
 9. The method according to claim 1, wherein the reaction solution and the ink composition are mixed together immediately before or immediately after ejection from an ink jet recording apparatus followed by printing on a recording medium.
 10. The method according to claim 1, wherein the reaction solution is a color ink containing a yellow ink dye, a cyan dye, or a magenta dye.
 11. A printed medium obtained by the method according to claim
 1. 12. In a method for forming print on a recording medium by depositing an ink composition and a reaction solution onto the recording medium so that the reaction solution reacts with the ink composition to form the print with desired properties, said ink composition comprising a colorant and an aqueous solvent, said reaction solution comprising a polyvalent metal salt or a polyallylamine, the improvement comprising providing the ink composition with an inorganic oxide colloid in an amount sufficient to form the print with an improved rubbing resistance or evenness of printing as compared to the print formed with the ink composition without the inorganic oxide colloid.
 13. The method according to claim 12, wherein the ink composition comprises the colorant in an amount of about 0.5 to 25% by weight and the inorganic oxide colloid in an amount of about 0.1 to 15% by weight; and wherein the reaction solution comprises water, an organic solvent in an amount of about 0.5 to 40% by weight and the polyvalent metal salt in an amount of about 0.1 to 40% by weight and/or the polyallylamine in an amount of about 0.5 to 10% by weight. 